The warning messages have gone when I used
a const object.  Thanks.

However the "unregistered class " crash still remains if the
if base/derived classes are placed in a static lib.  (for 1.42 only).

Robert Ramey wrote:
>EXPORT has been made a little bit more elabort to
>separate issues of code instantiation for class registration.  These
>changes were necessary to make EXPORT work properly with
>DLLS.  Look at the 1.42 documentation for an explanation.

Not sure I understand this.  In the 1.42 documentation
under "Export Key" it says:
"For programs which consist of only one module - that is programs which do not use DLLS, one can specify BOOST_CLASS_EXPORT(my_class) or BOOST_CLASS_EXPORT_GUID(my_class, "my_class_external_identifier") in either he declaration header or definition. These macros expand to invocation of the of both of the macros described above. (GUID stands for Globally Unique IDentfier.)"


So I am not using DLL's, and have used
      BOOST_CLASS_EXPORT(Derived);
in the implementation class.

So the work around for unix's looks like:
   1/ Place the BOOST_CLASS_EXPORT in the implementation
       and use explicit type registration
  2/ Place the BOOST_CLASS_EXPORT in the header _only_

In either case this is significant change, and should merit mention
in the 1.42 release notes, and a change to the documentation

  Best regards,
Ta,
   Avi